Abstract

With the recent surge of interest in the interaction between laser excited gas molecules and surfaces, little data exist on the probability of the excited molecule being deactivated upon a single collision with the surface. To date, information of this kind has been inferred from experiments in the diffusion regime. Here we report a new technique for the direct measurement of the probability of deactivation of an excited species by a surface. The reagent at pressures in the molecular flow regime is excited by a laser beam parallel to the surface. Comparison of the time decay of fluorescence with the surface first far from and then very near to the laser beam directly yields the probability of deactivation. For N0₂ (²B₂) excited by a dye laser at 592.5 nm, the deactivation probability is in the 0.3-1.0 range as determined by the decay of fluorescence at X > 600 nm. The dependence on surface temperature wili also be discussed. (13 min)

© 1981 Optical Society of America